Low-level electrical and communication interfaces to enable charging and discharging of electric vehicles with respect to the grid is described in U.S. Pat. No. 5,642,270 to Green et al., entitled, “Battery powered electric vehicle and electrical supply system,” incorporated herein by reference. The Green reference describes a bi-directional charging and communication system for grid-connected electric vehicles.
Modern automobiles, including electric vehicles, have many electronic control units for various subsystems. While some subsystems are independent, communications among others are essential. To fill this need, controller-area network (CAN or CAN-bus) was devised as a multi-master broadcast serial bus standard for connecting electronic control units. Using a message based protocol designed specifically for automotive applications, CAN-bus is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer. The CAN-bus is used in vehicles to connect the engine control unit, transmission, airbags, antilock braking, cruise control, audio systems, windows, doors, mirror adjustment, climate control, and seat control. CAN is one of five protocols used in the (On-Board Diagnostics) OBD-II vehicle diagnostics standard.
Modern vehicles contain a variety of subsystems that may benefit from communications with various off-vehicle entities. As the smart energy marketplace evolves, multiple application-level protocols may further develop for the control of power flow for electric vehicles and within the home. For example, energy management protocols are being developed for both Zigbee and Homeplug. A vehicle manufacturer may need to support multiple physical communications mediums. For example, ZigBee is used in some installations while PLC is used in others. Considering the very long service life of items such as utility meters and automobiles, the use of multiple incompatible protocols may pose an barrier to deployment. For example, if a homeowner buys a car that utilizes one protocol and receives a utility meter that uses another protocol, it is unlikely that either device will quickly replace other device.
Significant opportunities for improvement exist with respect to metering and translating measurements for power grids and electric vehicles. What is needed are systems and methods that provide for the efficient transfer of higher levels of information dealing with mobile populations of electric vehicles, the complexities of accurately metering such large populations.